The present invention relates generally to an expandable intraluminally implantable prosthesis. More particularly, the present invention relates to a radially supported graft/stent combination which may be intraluminally implanted in a minimally invasive procedure to repair or replace a damaged vessel of the vascular system.
It has long been known to employ intraluminally implantable prosthetic devices to repair or replace a damaged or diseased portion of a body lumen such as a blood vessel. Intraluminal implantation in a minimally invasive procedure permits such repair without the necessity of major surgical intervention. Typically, such implantation involves the use of a delivery system employed directly percutaneously or in other minimally invasive procedures, such as cut downs. In this manner, endovascular structures may be implanted by use of such a delivery system from a location remote from the damaged area. Intraluminal implantation in this manner greatly minimizes the risks inherent in major surgical implantation as it is less traumatic, less complicated, and generally a safer procedure. The prosthesis so delivered establishes a conduit which bridges the damaged portion of the vessel, thereby re-establishing blood flow therethrough without risk of further damage to the vessel. While vascular repair is one of the more common applications of an intraluminal prosthesis, such prosthesis may also be designed for use in other body lumens where repair is required.
The art has seen a wide variety of intraluminally deliverable prosthetic devices. Typically, these devices may include a tubular graft which is designed to span the damaged site of the vessel to permit blood flow therethrough. Such a graft is generally a compressible, flexible member which may be compressed or compacted into a small configuration so as to permit intraluminal delivery. In order to securely anchor the graft in place, the prosthesis may also include one or more stents attached to the graft itself. A stent is a compressible spring-like member which may be self-expanding such that when the prosthesis is deployed at its proper location, the stent expands so as to expand the graft into contact with the lumen to be repaired. The stent also serves to anchor the graft in place, thereby preventing migration of the prosthesis once the prosthesis is properly implanted.
An endovascular prosthesis employing a graft/stent combination which may be deliverable intraluminally via a delivery catheter is shown and described in U.S. Pat. No. 5,387,235, issued to Chuter. This patent describes a radially self-expandable prosthesis, including a woven, multi-filament polyester tubular graft which is supported by a spring assembly. The spring assembly includes individual stents at each end of the graft. A sheath is used to hold the graft and stents in a compressed condition so that it may be delivered intraluminally via the delivery catheter. Once properly located, the sheath is removed and the prosthesis is allowed to self-expand within the vessel across the damaged area. The individual stents may include outwardly directed barbs which anchor into the vessel securely positioning the prosthesis and preventing migration thereof.
The apparatus described in the ""235 patent serves adequately to implant a prosthesis intraluminally across a damaged vessel. However, as the graft is supported at spaced apart opposite ends thereof by the individual stents, the central portion of the graft is unsupported. Such unsupported central extent is subject to collapsing, kinking or folding, especially as the prosthesis traverses a tortuous path during implantation. Also, as separate spaced apart stents are employed at each end of the graft, it is possible for the stents to migrate axially relative to one another during implantation.
One attempt to address problems such as these in a percutaneously implantable prosthesis is shown in U.S. Pat. No. 5,282,824, issued to Gianturco. A graft/stent combination is disclosed where the spaced apart stents supporting opposed ends of the graft are connected by a single elongate rod. The single rod is designed to resist the contraction of the assembly along the longitudinal axis when the assembly is radially compressed and/or expanded. While the design of the stent assembly of the ""824 patent serves to maintain axial spacing between the spaced apart stents, the single rod connecting the stents offers little or no radial support to the graft positioned thereover. Thus, the prosthesis of the ""824 patent is still subject to kinking, collapsing or folding during and after implantation.
It is therefore desirable to provide a prosthesis including a stent/graft combination which provides adequate radial support from within the graft to maintain the graft in expanded condition without risk of collapsing, kinking or folding.
It is an object of the present invention to provide an implantable prosthetic device which may be implanted intraluminally without need for major surgical intervention.
It is a further object of the present invention to provide an intraluminally implantable stent/graft combination for use in repairing a damaged blood vessel.
It is a still further object of the present invention to provide an intraluminally implantable, self-expanding stent/graft combination which provides radial support for the graft so as to resist collapsing, kinking and folding during and after implantation.
In the efficient attainment of these and other objects, the present invention provides an implantable assembly. The assembly includes an elongate, generally tubular compressible graft having opposed end portions. A pair of resiliently compressible, generally tubular stents are positioned within the graft at spaced apart locations adjacent the end portions of the graft. A plurality of elongate struts extend between and interconnect the stents. The struts are radially spaced about the inner cylindrical surface of the graft and are designed for contact therewith, so as to provide internal radial support to the graft when in a compressed state and to further provide radial support along the length of the graft after implantation.
As more particularly described by way of the preferred embodiment herein, the graft is generally a textile graft having opposed open ends. A pair of stents, each formed by wire portions arranged in a zig-zag configuration, are disposed at the open ends of the graft. At least four struts are provided to span the central portion of the graft and interconnect the two stents. The struts are spaced such that they provide internal support for the graft, resisting kinking, collapsing or folding of the graft and also are spaced and arranged in such a manner that thrombosis formation between the struts is reduced.